Hard to say.
The port of Tartus on the Syrian coast is a Russian naval base and it's only military base outside of Russia after the collapse of the soviet union. So they obviously have some interests at stake.
The British also have a base on Cyprus at Akrotiri about 300 miles off the coast of Syria, so that asset and Israel might be subject to retaliation even if Syria's missiles do not have the requisite range. But we do not know that, China has been selling missiles to Syria for the last two decades.
If they somehow have this, then all of US military assets throughout the Mediterranean will easily be in range.
http://en.wikipedia.org/wiki/DH-10
The DongHai 10 (DH-10; Chinese: 东海-10; literally "East Sea-10") is a cruise missile developed in the People's Republic of China by the Third Academy by CASIC.
According to Janes, the DH-10 is a second-generation land-attack cruise missile (LACM), integrated inertial navigation system, GPS, terrain contour mapping system, and digital scene-matching terminal-homing system. The missile is estimated to have a circular error probable (CEP) of 10 meters. In 2008, a Pentagon report estimated the range of the DH-10 as over 4,000 km.